U.S. patent application number 13/088107 was filed with the patent office on 2011-11-24 for solar cell having reduced leakage current and method of manufacturing the same.
Invention is credited to Ku-Hyun Kang, Jung-Eun LEE.
Application Number | 20110284056 13/088107 |
Document ID | / |
Family ID | 44971430 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110284056 |
Kind Code |
A1 |
LEE; Jung-Eun ; et
al. |
November 24, 2011 |
SOLAR CELL HAVING REDUCED LEAKAGE CURRENT AND METHOD OF
MANUFACTURING THE SAME
Abstract
A solar cell having a reduced leakage current and a method for
fabricating the same are provided. The solar cell includes a
plurality of solar cells, and a plurality of cell division parts
dividing each of the plurality of solar cells. Each of the
plurality of solar cells includes a transparent electrode layer
formed on a substrate, a first photoelectric conversion layer
formed on the transparent electrode layer, an interlayer formed on
the first photoelectric conversion layer, first and second division
parts in which the interlayer is substantially absent, and a second
photoelectric conversion layer formed on the interlayer. The cell
division parts are formed within their respective second division
parts.
Inventors: |
LEE; Jung-Eun; (Goyang-si,
KR) ; Kang; Ku-Hyun; (Suwon-si, KR) |
Family ID: |
44971430 |
Appl. No.: |
13/088107 |
Filed: |
April 15, 2011 |
Current U.S.
Class: |
136/249 ;
257/E31.126; 438/73 |
Current CPC
Class: |
H01L 31/0465 20141201;
Y02E 10/548 20130101; H01L 31/076 20130101; H01L 31/046
20141201 |
Class at
Publication: |
136/249 ; 438/73;
257/E31.126 |
International
Class: |
H01L 31/042 20060101
H01L031/042; H01L 31/0224 20060101 H01L031/0224 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2010 |
KR |
10-2010-0048151 |
Claims
1. A solar cell comprising: a plurality of solar cells; and a
plurality of cell division parts dividing each of the plurality of
solar cells; wherein each of the plurality of solar cells includes:
a transparent electrode layer formed on a substrate; a first
photoelectric conversion layer formed on the transparent electrode
layer; an interlayer formed on the first photoelectric conversion
layer; first and second division parts in which the interlayer is
substantially absent; and a second photoelectric conversion layer
formed on the interlayer; and wherein the cell division parts are
formed within their respective second division parts.
2. The solar cell of claim 1, wherein the first photoelectric
conversion layer and the second photoelectric conversion layer
include a third division part overlapping the first division
part.
3. The solar cell of claim 2, wherein a width of the third division
part is smaller than a width of the first division part.
4. The solar cell of claim 2, wherein the third division part is
formed within the first division part.
5. The solar cell of claim 2, wherein the solar cell further
comprises a back surface electrode layer formed on the second
photoelectric conversion layer, wherein the back surface electrode
layer is formed while filling the third division part.
6. The solar cell of claim 1, wherein the second photoelectric
conversion layer fills at least portions of the first and second
division parts.
7. The solar cell of claim 1, wherein the transparent electrode
layer includes a fourth division part.
8. The solar cell of claim 7, wherein the first photoelectric
conversion layer fills the fourth division part.
9. A method for fabricating a solar cell, comprising: forming a
transparent electrode layer on a substrate; forming a first
photoelectric conversion layer on the transparent electrode layer;
forming an interlayer on the first photoelectric conversion layer
forming first and second division parts by patterning the
interlayer, the interlayer being substantially removed in the first
and second division parts; forming a second photoelectric
conversion layer on the interlayer; forming a third division part
by patterning the first and second photoelectric conversion layers;
and forming a cell division part within the second division part by
patterning the transparent electrode layer, and the first and
second photoelectric conversion layers.
10. The method of claim 9, wherein the forming of the first and
second division parts further comprises irradiating a patterning
light upon the interlayer.
11. The method of claim 10, wherein the patterning light comprises
ultraviolet (UV) laser light.
12. The method of claim 11, wherein a wavelength of the UV laser
light is in the range of about 300 to 400/.mu.m.
13. The method of claim 9, wherein the forming of the second
photoelectric conversion layer further comprises filling the first
and second division parts with the second photoelectric conversion
layer.
14. The method of claim 13, wherein the third division part is
formed within the first division part by patterning the first
photoelectric conversion layer and the second photoelectric
conversion layer.
15. The method of claim 14, wherein a distance between one side
wall of the first division part and one side wall of the third
division part is substantially equal to a distance between another
side wall of the first division part and another side wall of the
third division part.
16. The method of claim 13, wherein the forming cell division parts
further comprises patterning the transparent electrode layer, the
first photoelectric conversion layer, the second photoelectric
conversion layer filling the second division part, and the back
surface electrode layer.
17. The method of claim 16, wherein a distance between one side
wall of the second division part and one side wall of the cell
division part is substantially equal to a distance between another
side wall of the second division part and another side wall of the
cell division part.
18. The method of claim 9, further comprising forming a back
surface electrode layer on the second photoelectric conversion
layer, so as to fill the third division part with the back surface
electrode layer.
19. The method of claim 9, further comprising forming a fourth
division part by patterning the transparent electrode layer.
20. The method of claim 19, wherein the forming of the first
photoelectric conversion layer on the transparent electrode layer
comprises filling the fourth division part with the first
photoelectric conversion layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Korean Patent
Application No. 10-2010-0048151 filed on May 24, 2010 in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to solar cells. More
specifically, the present invention relates to solar cells having
reduced leakage current.
[0004] 2. Description of the Related Art
[0005] Solar cells, also known as photovoltaic cells, are elements
formed using, for example, semiconductor p-n junctions which
directly convert radiant energy from the sun into electrical
energy.
[0006] The p-n junction solar cell is based on the phenomenon by
which, when sunlight having higher energy than semiconductor
band-gap energy (Eg) is incident onto a solar cell, electron-hole
pairs are generated inside the semiconductor p-n junctions. That is
to say, the p-n junction solar cell uses electric power generated
between the p-n junctions when the electron-hole pairs are released
by incident sunlight, and electrons and holes of the generated
electron-hole pairs are collected in n-type and p-type
semiconductor layers, respectively, by electric fields formed in
the p-n junctions.
[0007] Meanwhile, a variety of attempts to investigate internal
structures of the solar cell are being made in order to improve
solar cell efficiency. One such structure, employing an interlayer
formed between a first photoelectric conversion layer and a second
photoelectric conversion layer, has been proposed to improve solar
cell efficiency. This proposed structure, however, has a problem of
current leakage, which may occur when the remainder of a lower
transparent electrode layer is shunted to the interlayer during
fabrication.
SUMMARY OF THE INVENTION
[0008] The present invention provides a solar cell having a reduced
leakage current.
[0009] The present invention also provides a method for fabricating
a solar cell having a reduced leakage current.
[0010] The above and other objects of the present invention will be
described in or be apparent from the following description of the
preferred embodiments.
[0011] According to an aspect of the present invention, there is
provided a solar cell including a plurality of solar cells, and a
plurality of cell division parts dividing each of the plurality of
solar cells. Each of the plurality of solar cells includes a
transparent electrode layer formed on a substrate, a first
photoelectric conversion layer formed on the transparent electrode
layer, an interlayer formed on the first photoelectric conversion
layer, first and second division parts in which the interlayer is
substantially absent, and a second photoelectric conversion layer
formed on the interlayer. The cell division parts are formed within
their respective second division parts.
[0012] According to another aspect of the present invention, there
is provided a method for fabricating a solar cell, the method
including forming a transparent electrode layer on a substrate,
forming a first photoelectric conversion layer on the transparent
electrode layer, and forming an interlayer on the first
photoelectric conversion layer. Also included is forming first and
second division parts by patterning the interlayer, the interlayer
being substantially removed in the first and second division parts,
forming a second photoelectric conversion layer on the interlayer,
and forming a third division part by patterning the first and
second photoelectric conversion layers. The method also includes
forming a cell division part within the second division part by
patterning the transparent electrode layer, and the first and
second photoelectric conversion layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other features and advantages of the present
invention will become more apparent by describing in detail
preferred embodiments thereof with reference to the attached
drawings in which:
[0014] FIG. 1 is a cross-sectional view of a solar cell according
to an aspect of the inventive concept of the present invention;
[0015] FIG. 2 is an enlarged view of an "A" portion of FIG. 1;
and
[0016] FIGS. 3 through 10 are cross-sectional views illustrating
intermediate process steps in a method for fabricating a solar cell
according to an aspect of the inventive concept of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Advantages and features of the present invention and methods
of accomplishing the same may be understood more readily by
reference to the following detailed description of preferred
embodiments and the accompanying drawings. The present invention
may, however, be embodied in many different forms and should not be
construed as being limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete and will fully convey the concept of the
invention to those skilled in the art, and the present invention
will only be defined by the appended claims. In the drawings, the
size and relative sizes of layers and regions may be exaggerated
for clarity. It will be understood that when an element is referred
to as being "on" another element, it can be directly on the other
element or intervening elements may be present therebetween. In
contrast, when an element is referred to as being "directly on"
another element, there are no intervening elements present.
[0018] Like reference numerals refer to like elements throughout
the specification. As used herein, the term "and/or" includes any
and all combinations of one or more of the associated listed
items.
[0019] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," or "includes"
and/or "including" when used in this specification, specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or
addition of one or more other features, regions, integers, steps,
operations, elements, components, and/or groups thereof.
[0020] Embodiments described herein will be described referring to
plan views and/or cross-sectional views by way of ideal schematic
views of the invention. Accordingly, the exemplary views may be
modified depending on manufacturing technologies and/or tolerances.
Therefore, the embodiments of the invention are not limited to
those shown in the views, but include modifications in
configuration formed on the basis of manufacturing processes.
Therefore, regions exemplified in figures have schematic properties
and shapes of regions shown in figures exemplify specific shapes of
regions of elements and not limit aspects of the invention.
[0021] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0022] Hereinafter, a solar cell according to an aspect of the
inventive concept of the present invention will be described in
further detail with reference to the accompanying drawings. FIG. 1
is a cross-sectional view of a solar cell according to an aspect of
the inventive concept of the present invention.
[0023] Referring to FIG. 1, the solar cell may include a plurality
of solar cells 100 and a plurality of cell division parts 65
dividing the solar cells 100.
[0024] Each of the solar cells 100 may include a substrate 10, a
transparent electrode layer 20, a first photoelectric conversion
layer 30, an interlayer 40, a second photoelectric conversion layer
50, and a back surface electrode layer 60.
[0025] The substrate 10 is a base element of a solar cell and is
generally made of an insulating material such as glass. In
particular, soda lime glass is preferably used as the substrate 10
for some applications, as soda lime glass is often low-cost and, as
is known, Na ions in the soda lime glass can act to improve solar
cell efficiency. Alternatively, the substrate 10 may be formed of a
ceramic substrate made of alumina. The substrate 10 may also be
made of stainless steel coated with an insulating material, or a
flexible polymer.
[0026] A transparent electrode layer 20 may be formed on the
substrate 10. Since the transparent electrode layer 20 allows
charges generated from the solar cell to flow outside, it may be
made of a transparent conductive oxide (TCO) having relatively low
contact resistance. Examples of the TCO may include SnO.sub.2, ZnO,
ITO, BZO, and so on.
[0027] In the solar cell 100 according to an aspect of the
inventive concept of the present invention, the transparent
electrode layer 20 may include a fourth division part 25, as shown
in FIG. 1. The fourth division part 25 is filled with the first
photoelectric conversion layer 30, which is further described
below.
[0028] The first photoelectric conversion layer 30 may be formed on
the transparent electrode layer 20. The first photoelectric
conversion layer 30 may be a photoelectric conversion layer made
of, for example, amorphous silicon (a-Si). In addition, although
not shown in FIG. 1, the first photoelectric conversion layer 30
may have a structure in which a first-conductivity type
semiconductor layer, an a-Si layer, and a second-conductivity type
semiconductor layer are sequentially stacked, but aspects of the
inventive concept of the present invention are not limited thereto.
Any suitable layer or set of layers is contemplated. The first
photoelectric conversion layer 30 may have various structures,
including a-Si. As described above, the first photoelectric
conversion layer 30 may fill the fourth division part 25.
[0029] The interlayer 40 may be formed on the first photoelectric
conversion layer 30. The interlayer 40 may be made of a
light-transmitting and light-reflecting material, e.g. a material
that both reflects and transmits light. Examples of the
light-transmitting and light-reflecting material may include
SnO.sub.2, ZnO, ITO, BZO, and so on.
[0030] As shown in FIG. 1, a first division part 45 and a second
division part 47 may be formed on the interlayer 40. The first
division part 45 may be formed to overlap a third division part 55
to be described later, and the second division part 47 may be
formed to overlap the cell division part 65, which will later be
described in more detail with reference to FIG. 2.
[0031] The second photoelectric conversion layer 50 may be formed
on the interlayer 40. As shown in FIG. 1, the second photoelectric
conversion layer 50 may be formed in at least portions of the first
division part 45 and the second division part 47 of the interlayer
40. Meanwhile, the second photoelectric conversion layer 50 may be
a photoelectric conversion layer made of, for example, amorphous
silicon (a-Si). Although not shown in FIG. 1, the second
photoelectric conversion layer 50 may have a structure in which a
first-conductivity type semiconductor layer, a crystalline Si
layer, and a second-conductivity type semiconductor layer are
sequentially stacked, but aspects of the inventive concept of the
present invention are not limited thereto. The second photoelectric
conversion layer 50 may have various structures, and any suitable
layer or set of layers is contemplated.
[0032] The back surface electrode layer 60 may be formed on the
second photoelectric conversion layer 50. The back surface
electrode layer 60 may function not only as an electrode layer but
also as a light reflecting layer. The back surface electrode layer
60 may be made of, for example, Ag or Al. The back surface
electrode layer 60 may be formed while filling the third division
part 55, as shown in FIG. 1.
[0033] Next, structures of the division parts 45, 47, 55, and 65 in
the solar cell according to the aspect of the inventive concept of
the present invention will be described.
[0034] FIG. 2 is an enlarged view of the portion "A" of FIG. 1.
[0035] Referring to FIG. 2, the third division part 55 formed in
the first photoelectric conversion layer 30 and the second
photoelectric conversion layer 50 may also be formed within the
first division part 45 of the interlayer 40. That is to say, the
third division part 55 may be formed to overlap the first division
part 45, where a width W3 of the third division part 55 is smaller
than a width W1 of the first division part 45. More specifically,
the third division part 55 may be formed within the first division
part 45, such that a distance L1 between one side wall of the first
division part 45 and one side wall of the third division part 55
may be equal to a distance L2 between the other side wall of the
first division part 45 and the other side wall of the third
division part 55, as shown in FIG. 2.
[0036] Meanwhile, the transparent electrode layer 20, the first
photoelectric conversion layer 30, the second photoelectric
conversion layer 50, and the cell division part 65 formed on the
back surface electrode layer 60 may be formed within the second
division part 47 of the interlayer 40. That is to say, the cell
division part 65 may be formed to overlap the second division part
47, where a width W4 of the cell division part 65 is smaller than a
width W2 of the second division part 47. More specifically, as
shown in FIG. 2, the cell division part 65 may be formed within the
second division part 47 such that a distance L3 between one side
wall of the second division part 47 and one side wall of the cell
division part 65 may be equal to a distance L4 between the other
side wall of the second division part 47 and the other side wall of
the cell division part 65.
[0037] As described above, FIG. 2 illustrates that the distance L1
between one side wall of the first division part 45 and one side
wall of the third division part 55 is equal to the distance L2
between the other side wall of the first division part 45 and the
other side wall of the third division part 55, and that the
distance L3 between one side wall of the second division part 47
and one side wall of the cell division part 65 is equal to the
distance L4 between the other side wall of the second division part
47 and the other side wall of the cell division part 65. However,
aspects of the inventive concept of the present invention are not
limited thereto. That is to say, in a solar cell according to
another aspect of the inventive concept of the present invention,
the distances L1 and L2 may or may not be equal to each other, and
likewise the distances L3 and L4 may or may not be equal to each
other.
[0038] As above, the cell division part 65 may be formed within the
second division part 47, and the third division part 55 may be
formed within the first division part 45. Therefore, even if a
portion of the transparent electrode layer 20 is removed during
formation of the cell division part 65 or the third division part
55, the transparent electrode layer 20 is unlikely to be shunted to
the interlayer 40, thereby preventing current leakage, which may
occur when the interlayer 40 is shunted to the transparent
electrode layer 20. That is, since the parts 55, 65 are formed in
regions in which the second photoelectric conversion layer 50
surrounds and protects interlayer 40, formation of parts 55, 65
does not result in any removed part of transparent electrode layer
20 contacting interlayer 40. In other words, as the interlayer 40
is substantially absent in the first and second division parts 45,
47 (having been removed from those areas prior to deposition of the
second photoelectric conversion layer 50 in those areas), and those
division parts 45, 47 are instead filled by the second
photoelectric conversion layer 50, the fabrication of cell division
parts 65 and third division part 55 does not result in any unwanted
conductive material contacting interlayer 40.
[0039] A method for fabricating a solar cell according to an aspect
of the inventive concept of the present invention will now be
described with reference to FIGS. 3 through 10.
[0040] FIGS. 3 through 10 are cross-sectional views illustrating
intermediate process steps in a method for fabricating a solar cell
according to an aspect of the inventive concept of the present
invention. In the following, repetitive descriptions of functional
components, including the material and configuration of each
component, which have already been described in the previous
embodiment of the solar cell shown in FIGS. 1 and 2 will be
omitted.
[0041] Referring first to FIG. 3, a transparent electrode layer 20
is formed on a substrate 10. Here, the transparent electrode layer
20 may be deposited on the substrate 10 by, for example, low
pressure chemical vapor deposition (LPCVD). The transparent
electrode layer 20 may be formed to a thickness in the range of
approximately 1 to 2 .mu.m.
[0042] Referring to FIG. 4, the transparent electrode layer 20 is
patterned to form a fourth division part 25. The fourth division
part 25 may be formed by irradiating patterning light, e.g., laser
light, on one surface of the transparent electrode layer 20. Here,
a width of the fourth division part 25 may be in the range of about
50 to 150 .mu.m.
[0043] Referring to FIG. 5, a first photoelectric conversion layer
30 may be formed on the transparent electrode layer 20. Here, the
first photoelectric conversion layer 30 may be deposited on the
transparent electrode layer 20 by, for example, chemical vapor
deposition (CVD). Meanwhile, the first photoelectric conversion
layer 30 may be formed to fill the fourth division part 25 formed
on the transparent electrode layer 20, as shown in FIG. 5.
[0044] Next, referring to FIG. 6, an interlayer 40 may be formed on
the first photoelectric conversion layer 30. The interlayer 40 may
be formed on the first photoelectric conversion layer 30 to a
thickness in a range of about 250 to 500 .ANG. by, for example,
LPCVD.
[0045] Referring to FIG. 7, the interlayer 40 is patterned to form
a first division part 45 and a second division part 47. The first
division part 45 and the second division part 47 may be formed by
irradiating patterning light on the upper surface of the interlayer
40. That is to say, the patterning light is irradiated in the
Y-direction in the embodiment illustrated in FIG. 7, thereby
forming the first division part 45 and the second division part 47
on the interlayer 40. This patterning process forms the first
division part 45 and the second division part 47 by substantially
removing the interlayer 40 in those areas. That is, the first
division part 45 and the second division part 47 are those areas in
which the interlayer 40 has been removed, and is thus substantially
absent.
[0046] In this case, the patterning light may be, for example, UV
laser light. Specifically, the patterning light may be UV laser
light having a wavelength in the range of, for example, about 300
to 400 .mu.m. More specifically, the patterning light may be UV
laser light having a wavelength of, for example, approximately 300
.mu.m. If the wavelength of the UV laser light is smaller than
about 300 .mu.m, the interlayer 40 may not be completely, or
properly, patterned. However, if the wavelength of the UV laser
light is greater than about 400 .mu.m, the irradiation of the UV
laser light may cause damage to the first photoelectric conversion
layer 30.
[0047] Referring to FIG. 8, a second photoelectric conversion layer
50 may be formed on the interlayer 40. Here, the second
photoelectric conversion layer 50 may be deposited on the
interlayer 40 by, for example, chemical vapor deposition (CVD).
Meanwhile, the second photoelectric conversion layer 50 may be
formed to fill the first division part 45 and the second division
part 47, as shown in FIG. 8.
[0048] Referring to FIG. 9, the first photoelectric conversion
layer 30 and the second photoelectric conversion layer 50 are
patterned to form a third division part 55. The third division part
55 may be formed by irradiating patterning light, e.g., laser
light, on one surface of the second photoelectric conversion layer
50. Here, a width of the third division part 55 according to the
aspect of the inventive concept of the present invention may be
smaller than that of the first division part 45, as shown in FIG.
9. In detail, the third division part 55 may be formed within the
first division part 45. With this configuration, even if a portion
of the transparent electrode layer 20 is removed during patterning
of the third division part 55, the transparent electrode layer 20
is unlikely to be shunted to the interlayer 40, thereby preventing
current leakage which may occur when the interlayer 40 is shunted
to the transparent electrode layer 20.
[0049] Next, referring to FIG. 10, a back surface electrode layer
60 may be formed on the second photoelectric conversion layer 50.
The back surface electrode layer 60 may be formed on the second
photoelectric conversion layer 50 by, for example, sputtering.
Forming the back surface electrode layer 60 may include filling the
third division part 55, as shown in FIG. 10. Accordingly, the third
division part 55 filled with the back surface electrode layer 60
may function as a contact of the solar cell.
[0050] Referring back to FIG. 1, the transparent electrode layer
20, the first and second photoelectric conversion layers 30 and 50,
and the back surface electrode layer 60 are patterned to form the
cell division part 65. The cell division part 65 may be formed by
irradiating patterning light, e.g., laser light, on one surface of
the back surface electrode layer 60. As shown in FIG. 1, a width of
the cell division part 65 according to the aspect of the inventive
concept of the present invention may be smaller than that of the
second division part 47. In detail, the cell division part 65 may
be formed within the second division part 47. With this
configuration, even if the remainder of the transparent electrode
layer 20 is evaporated while patterning the cell division part 65,
the transparent electrode layer 20 is unlikely to be shunted to the
interlayer 40, thereby preventing current leakage in the solar
cell.
[0051] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims. It is therefore desired that the present
embodiments be considered in all respects as illustrative and not
restrictive, reference being made to the appended claims rather
than the foregoing description to indicate the scope of the
invention.
* * * * *